Compression prestressed weld joints

Abstract

A compressively stressed weld joint joining a first tubular member to a second tubular member is formed by sequentially: (a) imparting stress into at least one of the tubular members such that release thereof will compressively stress the weld joint, (b) welding the first tubular member to the second tubular member, and (c) releasing the stress such that the weld is in compressive stress.

I claim: 
     
       1. A method for forming a compressively stressed weld joint joining a first tubular member to a second tubular member comprising sequentially: (a) imparting stress into at least one of the tubular members such that release thereof will compressively stress the weld joint,   (b) welding the first tubular member to the second tubular member, and   (c) releasing the stress imparted in step (a) such that the weld of step (b) is in compressive stress.   
     
     
       2. The method of claim 1 wherein: (a) the tubular members have a circular cross section along their long axis,   (b) the first tubular member is butt-welded to the side of the second tubular member at an angle of not less that 40°, and   (c) the butt end of the first tubular member is trimmed to fit the profile of the second tubular member at the site of welding.   
     
     
       3. The method of claim 2 wherein the angle is substantially 90°, wherein the members are comprised of steel, and wherein the members are part of an offshore platform. 
     
     
       4. The method of claim 2 wherein the cross section profile of the second tubular member along its long axis is deformed to provide elongation in the direction of the long axis of the first tubular member to impart stress into the second tubular member in accord with step (a) of claim 1. 
     
     
       5. The method of claim 4 wherein the angle is substantially 90°, wherein the members are comprised of steel, and wherein the members are part of an offshore platform.